Tinkering with the sequence of a protein that stimulates appetite, researchers have produced a super-potent version that greatly increases weight gain in rats (ACS Chem. Biol., DOI: 10.1021/cb2003412). The work may help scientists develop treatments for cachexia, a body wasting syndrome associated with diseases including cancer and AIDS.

When the body needs energy, a hunger hormone stimulates neurons in the hypothalamus to secrete the agouti-related protein. This protein . . .